Salinity Stress Treatments Research Articles

Investigation of the association between gene expression levels and phenolic compound content in the leaves of Sonchus arvensis plants under salinity stress

Sonchus arvensis is recognized for its high content of phenolic compounds and antioxidants, exhibiting various medicinal benefits, including anti-diabetic, anti-depressant, and anti-cancer properties. This has positioned the plant as a significant candidate for commercial food, medicinal, and antioxidant supplements. Salinity may enhance the level of chlorogenic and caffeic acid, which are key secondary metabolites in S. arvensis. To investigate this, a completely randomized design experiment with three replications was implemented in a greenhouse to examine the impact of salinity on the expression of six genes responsible for the biosynthesis of chlorogenic acid. Additionally, the study examined how salinity affects the accumulation of chlorogenic acid, caffeic acid, chicoric acid, and apigenin in the lower and middle leaves of plants. Salinity stress treatments were applied at four different levels: 0 (control), 50, 100, and 150 mM of NaCl. The results indicated that the expression levels of phenylalanine ammonia-lyase (PAL), cinnamate 4-hydroxylase (C4H), 4-coumarate-CoA ligase (4CL), and p-coumaroyl ester 3′-hydroxylase (C3′H) were highest in the middle leaves at a concentration of 150 mM NaCl. Notably, there was an eight-fold increase in C4H expression in these leaves under the same salinity conditions. Conversely, the expression of shikimate/quinate O-hydroxycinnamoyl transferase (HCT) and quinate O-hydroxycinnamoyl transferase (HQT) genes decreased across all salinity treatments. Additionally, the levels of chlorogenic acid, caffeic acid, and chicoric acid were significantly elevated at 50 mM NaCl in both the lower and middle leaves, suggesting that cultivating S. arvensis in mildly saline environments could be beneficial. Furthermore, the findings from this study may serve as a preliminary step towards the cloning and full characterization of the genes examined in S. arvensis.

Cerium Oxide Nanoparticles (CeO2 NPs) Enhance Salt Tolerance in Spearmint (Mentha spicata L.) by Boosting the Antioxidant System and Increasing Essential Oil Composition

Salinity represents a considerable environmental risk, exerting deleterious effects on horticultural crops. Nanotechnology has recently emerged as a promising avenue for enhancing plant tolerance to abiotic stress. Among nanoparticles, cerium oxide nanoparticles (CeO2 NPs) have been demonstrated to mitigate certain stress effects, including salinity. In the present study, the impact of CeO2 NPs (0, 25, and 100 mg L−1) on various morphological traits, photosynthetic pigments, biochemical parameters, and the essential oil profile of spearmint plants under moderate (50 mM NaCl) and severe (100 mM NaCl) salinity stress conditions was examined. As expected, salinity reduced morphological parameters, including plant height, number of leaves, fresh and dry weight of leaves and shoots, as well as photosynthetic pigments, in comparison to control. Conversely, it led to an increase in the content of proline, total phenols, malondialdehyde (MDA), hydrogen peroxide (H2O2), and antioxidant enzyme activities. In terms of CeO2 NP applications, they improved the salinity tolerance of spearmint plants by increasing chlorophyll and carotenoid content, enhancing antioxidant enzyme activities, and lowering MDA and H2O2 levels. However, CeO2 NPs at 100 mg L−1 had adverse effects on certain physiological parameters, highlighting the need for careful consideration of the applied concentration of CeO2 NPs. Considering the response of essential oil compounds, combination of salinity stress and CeO2 treatments led to an increase in the concentrations of L-menthone, pulegone, and 1,8-cineole, which are the predominant compounds in spearmint essential oil. In summary, foliar application of CeO2 NPs strengthened the resilience of spearmint plants against salinity stress, offering new insights into the potential use of CeO2 NP treatments to enhance crop stress tolerance.

Effects of salinity stress on physiological behavior, respiratory metabolism, and intestinal transcriptome of juvenile Stichopus monotuberculatus

This study investigated the impacts of salinity stress on the physiological behavior, respiratory metabolism, and transcriptome of artificially cultured juvenile Stichopus monotuberculatus (S. monotuberculatus) (with a body weight of 3.23 ± 0.60 g). S. monotuberculatus individuals cultured in artificial seawater were transferred to artificial seawater with salinities of 20‰, 30‰, and 40‰ for salinity stress treatment. The physiological behavior of S. monotuberculatus was observed, and their ammonia discharge rates, oxygen consumption rates, and oxygen/nitrogen (O/N) ratios were measured. After 24 h of stress, the intestines of S. monotuberculatus were collected for transcriptome sequencing. The results showed that both hyper-salinity and hypo-salinity stresses significantly affected the physiological status of S. monotuberculatus. The oxygen consumption and ammonia discharge rates of the hyper-salinity group (40‰) and hypo-salinity (20‰) group were remarkably higher than those of the control group (P<0.05), and the O/N ratios of the two groups were significantly lower than those of the control group (P<0.05). Sequencing identified a total of 3840 differentially expressed genes (DEGs) from the salinity-stress groups and the control group. GO analysis revealed that DEGs were mainly enriched in biological processes, cellular components, and molecular functional categories, with the highest enrichment observed in cellular processes, metabolic processes, membranes, binding, and catalytic activities. KEGG analysis showed that the DEGs of hyper-salinity and hypo-salinity groups were enriched in different secondary pathways, with the expressions of related genes significantly upregulated, indicating that S. monotuberculatus may adapt to hyper-salinity and hypo-salinity environments through various regulatory mechanisms. The results verify that salinity stress significantly affects the physiological behavior and respiratory metabolism of S. monotuberculatus. S. monotuberculatus respond to hyper-salinity and hypo-salinity stresses by increasing protein consumption and adopting different adaptation mechanisms. Furthermore, S. monotuberculatus exhibits stronger tolerance to hypo-salinity environments compared to hyper-salinity ones.

Effects of Dietary Inosine 5'-Monophosphate Supplementation on the Growth Performance and Salinity and Oxidative Stress Resistance of Gibel Carp (Carassius auratus gibelio).

An 88-day feeding trial was conducted to evaluate the effects of dietary inosine 5'-monophosphate (5'-IMP) on the growth performance and salinity and oxidative stress resistance in the juvenile gibel carp CAS III (Carassius auratus gibelio; initial body weight: 7.48 g). Four isonitrogenous and isoenergetic diets containing exogenous 5'-IMP were formulated. P1, P2, P3 and P4 were diets containing 5'-IMP at four concentrations (0, 1, 2 and 4 g kg-1). The four diets were randomly allotted to triplicate tanks in a recirculating system. After the feeding trial, six fish per tank were netted randomly and placed into 12‱ saline water to test their response to salinity stress. The results indicated that the feed conversion rate was enhanced by dietary supplementation with 5'-IMP. The appetite, plasma neuropeptide Y level and feeding rate of the P3 group were lower than those in the control treatment group. Dietary supplementation with 5'-IMP improved the osmoregulatory adaptation of gibel carp under acute salinity stress. Six hours after the salinity stress treatment, in the dietary 5'-IMP treatment group, the plasma cortisol and K+ concentrations were lower and the Na+/K+-ATPase activity was greater than that in the control group. Dietary supplementation with 5'-IMP promoted the expression of the glucocorticoid receptors NKA-α1b and NKCC and retarded the expression of Hsp70 in P4-treated gill filaments and kidneys. Dietary supplementation with 5'-IMP resulted in a stable oxidative-stress-resistant phenotype characterized by increased levels of cellular antioxidants, including SOD, catalase, glutathione peroxidase, glutathione reductase and MPO. The above results of the current study demonstrate that supplementation of 5'-IMP can promote feed utilization and have positive influences on the salinity and oxidative stress resistance of gibel carp.

Effect of salinity stress and surfactant treatment with zinc and boron on morpho-physiological and biochemical indices of fenugreek (Trigonella foenum-graecum)

Micronutrient application has a crucial role in mitigating salinity stress in crop plants. This study was carried out to investigate the effect of zinc (Zn) and boron (B) as foliar applications on fenugreek growth and physiology under salt stress (0 and 120 mM). After 35 days of salt treatments, three levels of zinc (0, 50, and 100 ppm) and two levels of boron (0 and 2 ppm) were applied as a foliar application. Salinity significantly reduced root length (72.7%) and shoot length (33.9%), plant height (36%), leaf area (37%), root fresh weight (48%) and shoot fresh weight (75%), root dry weight (80%) and shoot dry weight (67%), photosynthetic pigments (78%), number of branches (50%), and seeds per pod (56%). Fenugreek’s growth and physiology were improved by foliar spray of zinc and boron, which increased the length of the shoot (6%) and root length (2%), fresh root weight (18%), and dry root weight (8%), and chlorophyll a (1%), chlorophyll b (25%), total soluble protein content (3%), shoot calcium (9%) and potassium (5%) contents by significantly decreasing sodium ion (11%) content. Moreover, 100 ppm of Zn and 2 ppm of B enhanced the growth and physiology of fenugreek by reducing the effect of salt stress. Overall, boron and zinc foliar spray is suggested for improvement in fenugreek growth under salinity stress.

Enhanced azadirachtin production in neem (Azadirachta indica) callus through NaCl elicitation: Insights into differential protein regulation via shotgun proteomics

With their remarkable bioactivity and evolving commercial importance, plant secondary metabolites (PSMs) have gained significant research interest in recent years. Plant tissue culture serves as a credible tool to examine how abiotic stresses modulate the production of PSMs, enabling clear insights into plant stress responses and the prospects for controlled synthesis of bioactive compounds. Azadirachta indica, or neem has been recognized as a repository of secondary metabolites for centuries, particularly for the compound named azadirachtin, due to its bio-pesticidal and high antioxidant properties. Introducing salt stress as an elicitor makes it possible to enhance the synthesis of secondary metabolites, specifically azadirachtin. Thus, in this research, in vitro callus cultures of neem were micro-propagated and induced with salinity stress to explore their effects on the production of azadirachtin and identify potential proteins associated with salinity stress through comparative shotgun proteomics (LCMS/MS). To induce salinity stress, 2-month-old calli were subjected to various concentrations of NaCl (0.05–1.5%) for 4 weeks. The results showed that the callus cultures were able to adapt and survive in the salinity treatments, but displayed a reduction in fresh weight as the NaCl concentration increased. Notably, azadirachtin production was significantly enhanced in the salinity treatment compared to control, where 1.5% NaCl-treated calli produced the highest azadirachtin amount (10.847 ± 0.037 mg/g DW). The proteomics analysis showed that key proteins related to primary metabolism, such as defence, energy, cell structure, redox, transcriptional and photosynthesis, were predominantly differentially regulated (36 upregulated and 93 downregulated). While a few proteins were identified as being regulated in secondary metabolism, they were not directly involved in the synthesis of azadirachtin. In conjunction with azadirachtin elicitation, salinity stress treatment could therefore be successfully applied in commercial settings for the controlled synthesis of azadirachtin and other plant-based compounds. Further complementary omics approaches can be employed to enhance molecular-level modifications, to facilitate large-scale production of bioactive compounds in the future.

Salt stress memory in tall fescue: Interaction of different stress stages, pollination system and genetic diversity.

The effects of salinity memory and its interaction with genetic diversity for drought tolerance and pollination system in terms of morphological, physiological, root characteristics and spectral reflectance indices (SRIs) in tall fescue is still unknown. Four tall fescue genotypes (two drought-sensitive and two drought-tolerant) were manually controlled to produce four selfed (S1) and four open-pollinated (OP) progeny genotypes (finally eight progeny genotypes). Then all genotypes were assessed for two years in greenhouse under five salinity treatments including control treatment (C), twice salinity stress treatment (primary mild salinity stress in two different stages and secondary at the end stage) (S1t1S2 and S1t2S2), once severe salinity stress treatment (secondary only, S2), and foliar spray of salicylic acid (SA) simultaneously with secondary salinity stress (H2S2). Results indicated that obligate selfing (S1) caused to inbreeding depression in RWC, plant growth, catalase activity, root length and the ratio of root/shoot (R/S). Once salinity stress treatment (S2) led to depression in most measured traits, while pre-exposure to salinity (salinity memory) (S1t1S2 and S1t2S2) improved photosynthetic pigments, proline, antioxidant enzymes and R/S. Salinity memory was more pronounced in drought-sensitive genotypes, while it was more evident in OP than S1 population. Foliar spray of salicylic acid (SA) was almost equally effective in reducing the effects of salinity stress in both populations. The efficacy of application was more pronounced in tolerant genotypes compared to sensitive ones. The possibility of modeling correlated spectral reflectance indices (SRIs) for prediction of different morphological, physiological and root characteristics will be discussed.

Differential Gene Expression Responses to Salt and Drought Stress in Tall Fescue (Festuca arundinacea Schreb.).

Understanding gene expression kinetics and the underlying physiological mechanisms in stress combinations is a challenge for the purpose of stress resistance breeding. The novelty of this study is correlating the physiological mechanisms with the expression of key target genes in tall fescue under a combination of various salinity and osmotic stress treatments. Four drought- and salt-responsive genes belonging to different crucial pathways evaluated included one transcription factor FabZIP69, one for the cytosolic polyamine synthetase FaADC1, one for ABA signaling FaCYP707A1, and another one for the specific Na+/H+ plasma membrane antiporter FaSOS1 involve in osmotic homeostasis. FaSOS1, FaCYP707A1, and FabZIP69 were induced early at 6h after NaCl treatment, while FaSOS1 and FaCYP707A1 were transcribed gradually after exposure to PEG. However, stress interactions showed a significantly increased expression in all genes. Expression of these genes was positively correlated to Pro, SSs, IL, DPPH, and antioxidant enzyme activity and negatively correlated with RWC, total Chl, and MSI. Chemical analyses showed that tall fescue plants exposed to the combination of stresses exhibited increased quantity of reactive oxygen species (H2O2), EL and DPPH, and higher levels of antioxidant enzyme activities (CAT, and SOD), Pro, and SSs content, compared with control seedlings. Under dual-stress conditions, the expression of FabZIP69 was effective in controlling the expression of FaSOS1 and FaADC1 genes differently.

Effects of acute salinity stress on physiology and immunoenzymatic activity in juvenile sea cucumber, Stichopus monotuberculatus

To investigate the effects of acute salinity stress on physiology and immunoenzymatic activity in juvenile sea cucumbers, Stichopus monotuberculatus and S. monotuberculatus with body weights of 12.6 ± 3.1 g were selected as study subjects, and a salinity of 30‰ was used as the control, while salinities of 20‰, 25‰, 35‰ and 40‰ were used as acute salinity stress treatment groups. The survival rate of S. monotuberculatus was calculated, histological changes in the intestines were observed, and the activities of superoxide dismutase (SOD), catalase (CAT), and alkaline phosphatase (AKP) in the coelomic fluid, as well as Na+/K+-ATPase in the intestine, were measured and analyzed. The results showed that juvenile S. monotuberculatus could survive at salinities of 20–35‰, and could only survive for 24 h at a salinity of 40‰. Both high and low salinity stress changed the intestinal morphology of S. monotuberculatus, as epithelial cells were damaged and necrotic, vacuolated in the intestinal villi, and had unclear brush border edges. At 6 h after salinity stress, SOD and CAT activities in coelomic fluid increased or decreased rapidly and then adjusted and recovered gradually with the extension of stress time. SOD activity in the low-salinity groups was significantly higher than that in the control group, and CAT activity was significantly higher in the low-salinity groups (20‰ and 25‰) than in the high-salinity groups (35‰ and 40‰). AKP activity in the coelomic fluid was inhibited in the low-salinity groups and showed a gradual increase with increasing salinity. Na+/K+-ATPase activities in intestines showed a slow increase in the 20‰ salinity group and then dropped back to control levels. In the other salinity groups, Na+/K+-ATPase activity was higher at 6 h and 48 h after salinity stress. The results obtained from the present study indicate that salinity stress affected the survival rate and intestinal morphology of S. monotuberculatus, and S. monotuberculatus could respond to external environmental changes by regulating the activities of antioxidant enzymes, Na+/K+-ATPase, and AKP.

Physiological and Molecular Analysis Revealed the Role of Silicon in Modulating Salinity Stress in Mung Bean

Salinity stress acts as a significant deterrent in the course of optimal plant growth and productivity, and mung bean, being a relay crop in the cereal cropping system, is severely affected by salinity. Silicon (Si), on the other hand, has exhibited promising outcomes with regards to alleviating salinity stress. In order to understand the critical mechanisms underlying mung bean (Vigna radiata L.) tolerance towards salt stress, this study examined the effects of different salinity concentrations on antioxidant capacity, proteome level alterations, and influence on Si-transporter and salt-responsive genes. Salinity stress was seen to effect the gaseous exchange machinery, decrease the soluble protein and phenolic content and NR activity, and increase the accumulation of reactive oxygen species. An efficient regulation of stomatal opening upon Si application hints towards proficient stomatal conductance and CO2 fixation, resulting in efficient photosynthesis leading to proficient plant growth. The soluble protein and phenolic content showed improved levels upon Si supplementation, which indicates an optimal solute transport system from source to sink. The content of superoxide radicals showed a surge under salinity stress treatment, but efficient scavenging of superoxide radicles was noted under Si supplementation. Salinity stress exhibited more damaging effects on root NR activity, which was notably enhanced upon Si supplementation. Moreover, the beneficial role of Si was further substantiated as there was notable Si accumulation in the leaves and roots of salinity-stressed mung bean plants. Furthermore, Si stimulated competent ROS scavenging by reinforcing the antioxidant enzyme activity, as well coordinating with their isozyme activity, as expressed by the varying band intensities. Similarly, the Si-mediated increase in peroxidase activity may reveal changes in the mechanical characteristics of the cell wall, which are in turn associated with salinity stress adaptation. Proteomic investigations revealed the upregulation or downregulation of several proteins, which were thereafter identified by LC−MS/MS. About 45 proteins were identified and were functionally classified into photosynthesis (24%), metabolic process (19%), redox homeostasis (12%), transmembrane transport (10%), stress response (7%), and transcription regulation (4%). The gene expression analysis of the silicon transporter genes (Lsi1, Lsi2, and Lsi3) and SOS pathway genes (SOS1, SOS2, and SOS3) indicated the role of silicon in mitigating salinity stress. Hence, the findings of this study can facilitate a profound understanding of the potential mechanisms adopted by mung bean due to exogenous Si application during salinity stress.

Data-Mining of Barley to Identify Salt Stress Hub Genes, Gene Expression Analysis and Recombinant Plasmid Construction.

Salinity is one of the major abiotic stresses that limit the production and yields of agricultural crops worldwide. In order to identify key barley genes under salinity stress, the available metadata were examined by two methods of Cytoscape and R software. Next, the hub expression of the selected gene was evaluated under different salinity stress treatments and finally, this gene was cloned into cloning and expression vector and recombinant plasmid was made. In this study, we extracted salinity stress tolerant genes from several kinds of literature and also microarray data related to barley under salinity conditions from various datasets. The list of genes related to literature analyzed using string and Cytoscape. The genes from the datasets were first filtered and then the hub genes were identified by Cytoscape and R methods. Next, these hub genes were analyzed for the promoter. Ten hub genes were selected and their promoters were analyzed, the cis-element of which was often cis-acting regulatory element involved in the methyl jasmonate -responsiveness, common cis-acting element in promoter and enhancer regions and MYBHv1 binding site. Finally, the sedoheptulose-1,7-bisphosp gene (SBPase), which had the highest interaction in both gene lists and both types of gene networks, was selected as hub gene. Next, the expression of SBPase gene was examined in two variety of Youssef variety (salt tolerant) and Fajr variety (salt sensitive) under salinity stress (NaCl 100mM) at 0 (control), 3, 6, 12 and 24 hours after stress. The results showed that the expression of this gene increased with increasing the duration of stress in both varieties. Comparison of the two varieties showed that the expression of SBPase gene in the tolerant genotype was twice as high as sensitive. Finally, SBPase gene as a key gene for salinity stress was cloned in both cloning (pTG19) and expression (pBI121) vectors. According to our results, SBPase gene increased growth and photosynthesis in barley under various abiotic stresses, therefore, over-expression of this gene in barley is recommended to produce plants resistant to abiotic stresses.

The Application of endophytic halotolerant bacteria in modulating the development of maize seedlings under salinity

Salinity stress has negative effects on plants physiologically as well as lowering productivity. Application of microbial inoculant as seed treatment is one of the bio-techniques that have proved to be efficient in enhancing salinity resilience in agriculture, especially for seedling development. This study aims to determine the effect of inoculation of halotolerant bacteria consortium on the development of maize seedlings under saline stress. The experiment used four different bacterial consortia namely B5 (two species of phosphate solubilizing bacteria); B6 (phosphate solubilizing bacteria, and ACC deaminase producing bacteria); B7 (phosphate solubilizing bacteria and nitrogen-fixing bacteria) and B9 (phosphate solubilizing bacteria, ACC deaminase producing bacteria and nitrogen-fixing bacteria). The salinity stress was conducted by adding NaCl with a concentration of 0, 50, 100, and 150 mM to the Hoagland nutrient solution as a germination medium. The inoculation bacteria increased the root length, root number, shoot length, fresh weight, and chlorophyll content of Pioneer maize seedling up to 25% at salinity stress treatment 150 mM NaCl. The highest increase in seedlings growth parameters was observed on seedlings inoculated by B5, B7, and B9 under a salinity treatment of 150 mM.

Physiological and anatomical response of rice (Oryza sativa L.) ‘Hom Mali Daeng’ at different salinity stress levels

Abstract Soil salinity is a severe global stressor causing adverse impacts on irrigated land and drastically reducing crop yields, especially in rice, an important economic crop of Thailand. In this study, the impacts of salt stress on the anatomical and physiological features of 28-day-old rice (Oryza sativa L.) ‘Hom Mali Daeng’ were determined. Various NaCl concentrations (0, 50, 100, 150, and 200 mM) were applied every 2 days, with watering for 2 weeks. The results revealed that salinity stress inhibited the growth of rice. Leaf number, root size, fresh weight, and dry weight were significantly reduced. The electrolyte leakage percentage and malondialdehyde (MDA) content increased after treatment with high NaCl concentrations, while the SPAD unit and chlorophyll content were not significantly different between the control and NaCl treatments. Leaf anatomy changes were studied using freehand section and peeling techniques after salinity stress treatment. Lamina thickness in all treatments decreased, while cell wall and cuticle thickness increased. Stomatal density in all treatments significantly increased. Major vascular bundle, vessel, and phloem area of the 100 mM NaCl treatment were different when compared with the control and other treatments. The results provide information about the physiological and anatomical adaptation of ‘Hom Mali Daeng’ rice, which will be useful for further research in this and other rice cultivars.

Chalcone synthase (CHS) family genes regulate the growth and response of cucumber (Cucumis sativus L.) to Botrytis cinerea and abiotic stresses

The chalcone synthase (CHS) gene family is instrumental not only regulating plant growth and development but fine-tuning plant response to environmental hazards. Despite the growing body of literature, the role of CHS genes in cucumber (Cucumis sativus L.) remains elusive. Herein, we identified 4 CsCHS genes from the cucumber genome database. The evolutionary relationship, gene structure, conserved motifs, proteins interaction and chemical properties highlight the key aspects of CsCHS genes in cucumbers. Evolutionary tree analysis reveals that the CsCHS family is divided into four clades. Moreover, the Gene Ontology (GO) analysis showed that CsCHS genes regulate plant growth and response to various environmental stimuli. Microarray expression data showed that CsCHS genes were expressed in almost all the tested tissues. Additionally, the differential expression patterns of the CsCHS genes were found under salinity stress and hormonal treatments. The qRT-PCR analysis of CsCHS genes under aphid infestation revealed they are key components of plant defense against insect pests. Under waterlogging stress, only the CsCHS3 displayed high expression under naphthalene acetic acid (NAA) and ethylene (ETH). The dual luciferase assay indicated that CsCHS2 effectively binds to the promoters of key stress markers CsERF1 and CsERF3. Our results have provided detailed knowledge regarding the CsCHS gene's influential role in growth and development and also providing the resistive defense in cucumber plants. We believe our study will facilitate the breeding of stress-resilient cultivars, particularly against insect pests and waterlogging stress.

Study on germination and seedling growth of various ecotypes of fennel (Foeniculum vulgare Mill.) under salinity stress

Salinity is one of the most brutal environmental factors limiting the productivity of crops and cultivation of salt-tolerant plants has been suggested as one of the strategies for reducing the effects of salinity and utilizing saline soil and water resources. This experiment was conducted in two separate experiments, one in the laboratory to study germination and the other in the greenhouse to study seedling characteristics of various fennel ecotypes (Foeniculum vulgare) in 2020. Laboratory experiment was performed in factorial base on completely randomized design with three replications and two factors. Factors included four salinity concentrations (0, 4, 8, and 12 dSm−1) and 19 fennel ecotypes (Lorestan, Kermanshah, Kashan, Damavand-Tehran, Khoramabad, Arak, Ardabil-Kalibar, Bandarabas, Ardabil, Zanjan, Tehran-Karaj, Tehran, Rodan-Hormozgan, Yazd, Shiraz, Qazvin, Khash-Sistan, Hamadan, and Isfahan). From laboratory experiment, three salt-sensitive ecotypes (Yazd, Kermanshah, and Bandarabas) and three salt-tolerant ecotypes (Isfahan, Khash-Sistan, and Rodan-Hormozgan) were identified. Greenhouse experiment was performed in factorial base on completely randomized design with three replications and two factors. Factors included four salinity concentrations (0, 4, 8, and 12 dSm−1) and six fennel ecotypes (Isfahan, Khash-Sistan, Rodan-Hormozgan, Yazd, Kermanshah, and Bandarabas). At both experiments, sodium chloride (NaCl) and calcium chloride (CaCl2) were used in two-to-one ratios to apply salinity stress treatments. The results showed that salinity decreased the mean daily germination, germination percentage, and germination rate compared with control conditions and the lowest amounts of these traits were observed at the salinity of 12 dSm−1. Salinity reduced the fresh and dry weights of roots, shoots, and total, root volume, root and shoot lengths, leaf area, relative water content, and chlorophyll content. Whereas, the amount of proline, and the ratio of sodium to potassium content of roots and shoots increased. The Khash-Sistan ecotype had the highest root fresh and dry weights, root volume, root length, and leaf area and the Bandarabbas ecotype had the lowest root fresh and dry weights, root volume, and leaf area. Also, salinity had less negative effect on traits such as relative water content and chlorophyll a, b, and a+b in the Khash-Sistan ecotype, and more negative effects on relative water content in the Bandarabas ecotype. Therefore, the Khash-Sistan ecotype was identified as a salt-tolerant ecotype and the Bandarabas ecotype was identified as a salt-sensitive ecotype.

Knockout Mutants of OsPUB7 Generated Using CRISPR/Cas9 Revealed Abiotic Stress Tolerance in Rice.

Plants produce and accumulate stress-resistant substances when exposed to abiotic stress, which involves a protein conversion mechanism that breaks down stress-damaged proteins and supplies usable amino acids. Eukaryotic protein turnover is mostly driven by the ubiquitination pathway. Among the three enzymes required for protein degradation, E3 ubiquitin ligase plays a pivotal role in most cells, as it determines the specificity of ubiquitination and selects target proteins for degradation. In this study, to investigate the function of OsPUB7 (Plant U-box gene in Oryza sativa), we constructed a CRISPR/Cas9 vector, generated OsPUB7 gene-edited individuals, and evaluated resistance to abiotic stress using gene-edited lines. A stress-tolerant phenotype was observed as a result of drought and salinity stress treatment in the T2OsPUB7 gene-edited null lines (PUB7-GE) lacking the T-DNA. In addition, although PUB7-GE did not show any significant change in mRNA expression analysis, it showed lower ion leakage and higher proline content than the wild type (WT). Protein-protein interaction analysis revealed that the expression of the genes (OsPUB23, OsPUB24, OsPUB66, and OsPUB67) known to be involved in stress increased in PUB7-GE and this, by forming a 1-node network with OsPUB66 and OsPUB7, acted as a negative regulator of drought and salinity stress. This result provides evidence that OsPUB7 will be a useful target for both breeding and future research on drought tolerance/abiotic stress in rice.

Circadian Clock Contributes to Modulate Salinity Stress-Responsive Antioxidative Mechanisms and Chloroplast Proteome in Spinacia oleracea

Extreme abiotic stresses such as drought, salinity, and temperature reduce crop productivity significantly and pose a serious threat to the area of land used for agriculture. Therefore, there is a pressing need to create crops that can thrive in these circumstances. It has been noted that plants can maintain defense mechanisms during any environmental changes and anticipate diurnal patterns correct to a circadian-based clock. Therefore, the main aim of this study was to investigate the role of circadian core oscillators in response to salinity stress in an important vegetable crop, spinach, and obtain evidence to better understand salinity stress adaptation for crop productivity. Therefore, the current study was carried out to examine the circadian clock-based (morning–evening loop) salinity stress defense mechanism in spinach (Spinacia oleracea), a leafy vegetable crop with significant economic importance and health benefits. In the presence of dawn and dusk, the circadian clock-based defense mechanism was observed using the genotypes “Delhi Green” and “Malav Jyoti.” A photoperiodic rhythm consists of 4-h intervals for 12 h (morning–evening loop) in spinach was demonstrated under the salinity stress treatments (20 mM and 50 mM). The clock-controlled a large fraction of growth parameters such as plant height, biomass, and root-shoot ratio under salinity stress. Conversely, salinity stress resulted in upregulation of antioxidative parameters such as superoxide dismutase, ascorbate peroxidase, catalase, and other stress markers such as thiobarbituric acid reactive substances, proline content, and localizations of H2O2 and O2−1 but was altered and maintained at a certain photoperiodic time interval of the circadian clock. In distinction to results observed from antioxidative measurements performed with an early and late circadian duration of salt-treated plants, 10 am and 2 pm were revealed to be the rhythmic times for controlling salinity stress. Likewise, comprehensive measurements of the photosynthetic system under salinity stress at specific photoperiodic circadian time intervals, including net-photosynthetic rate, transpiration, stomatal conductance, PSII quantum yield, and stomata structure, were made at 10 am and 2 pm. The salinity stress response was down-streamed and the clock also regulated chloroplastic protein expression. Thus, according to our findings, photoperiodic circadian rhythms, particularly the morning–evening loop, enhanced plant survival rates by modulating cellular antioxidant mechanisms and chloroplastic proteins that further helped to reduce the effects of salinity stress.

Differential Effect of Heat Stress on Drought and Salt Tolerance Potential of Quinoa Genotypes: A Physiological and Biochemical Investigation.

Soil salinity, drought, and increasing temperatures are serious environmental issues that drastically reduce crop productivity worldwide. Quinoa (Chenopodium quinoa Willd) is an important crop for food security under the changing climate. This study examined the physio-biochemical responses, plant growth, and grain yield of four quinoa genotypes (A7, Titicaca, Vikinga, and Puno) grown in pots containing normal (non-saline) or salt-affected soil exposed to drought and elevated-temperature treatments. Combinations of drought, salinity, and high-temperature stress decreased plant growth and yield more than the individual stresses. The combined drought, salinity, and heat stress treatment decreased the shoot biomass of A7, Puno, Titicaca, and Vikinga by 27, 36, 41, and 50%, respectively, compared to that of control plants. Similar trends were observed for grain yield, chlorophyll contents, and stomatal conductance. The combined application of these three stresses increased Na concentrations but decreased K concentrations in roots and shoots relative to control. Moreover, in the combined salinity, drought, and high-temperature treatment, A7, Puno, Titicaca, and Vikinga had 7.3-, 6.9-, 8-, and 12.6-fold higher hydrogen peroxide contents than control plants. All four quinoa genotypes increased antioxidant enzyme activities (CAT, SOD, and POD) to overcome oxidative stress. Despite A7 producing the highest biomass under stress, it did not translate into increased grain production. We conclude that Puno and Titicaca are more tolerant than Vikinga for cultivation in salt-affected soils prone to drought and heat stress.

Seed Priming with Nanoparticles and 24-Epibrassinolide Improved Seed Germination and Enzymatic Performance of Zea mays L. in Salt-Stressed Soil

Saline stress is one of the most critical abiotic stress factors that can lessen crops' productivity. However, emerging nanotechnology, nano-fertilizers, and developing knowledge of phytochromes can potentially mitigate the negative effects of saline stress on seed germination. Therefore, the aim of this study was to investigate the effects of seed priming either with zinc oxide nanoparticles (ZnO-NPs; 50 and 100 mg L-1) or 24-epibrassinolide (EBL; 0.2 and 0.4 μM) and their combinations on maize (Zea mays L.) grains sown in salt-stressed soil (50 and 100 mM NaCl). Saline stress treatments significantly affected all germination traits and chemical analysis of seeds as well as α-amylase activity. Compared to un-primed seeds, seed priming with ZnO-NPs or EBL and their combinations significantly increased the cumulative germination percentage, germination energy, imbibition rate, increase in grain weight, K+ content, and α-amylase activity, and significantly reduced germination time, days to 50% emergence, Na+ uptake, and Na+/K+ ratio of maize sown in salt-stressed-soil (50 or 100 mM NaCl). The combination of 100 mg ZnO-NPs L-1 + 0.2 μM EBL resulted in the highest improvements for most of the studied traits of maize seeds sown in salt-stressed soil in comparison to all other individual and combined treatments.

Enhancement of lipid yield in &lt;em&gt;Chlorella&lt;/em&gt; sp. under different stress conditions for the production of biodiesel

Microalgae derived bio-lipids can be potentially converted to biofuel using appropriate technologies. However, optimum conditions for enhancing the growth of microalgae often lead to relatively low accumulation of bio-lipids. Alternatively, stress conditions favor the storage of lipids despite the low biomass yield. For commercial production of microalgae derived biofuel, the unit cost of production of biodiesel should be lower than that of petro diesel. The aim of the present study was to enhance the lipid yield of <em>Chlorella</em> sp. by introducing various stress conditions such as nitrogen deficiency, zinc deficiency and excessive salinity in the growth media. Conventional Bold’s Basal Media (BBM) was used as the culture media in all the experimental conditions. Five treatments were used namely; normal Bold’s basal media, three times concentration enhanced Bold’s basal media, Nitrogen deficient media, Zinc deficient media and Salinity stress media. Light intensity was kept constant in all the experimental conditions. Air mixing was provided using spargers in all test conditions to keep the microalgae cultures in suspension. All the reactors were maintained in similar growth conditions in the first phase and the stress conditions were introduced in the second phase after 7 days. The microalgae biomass was harvested on 4th, 8th, 11th, 14th and 17th day of cultivation for the determination of lipids. A Chloroform: Methanol mixture with 1:1 ratio was used to extract lipids from dried biomass using Soxhlet extractor. A considerable increase in the lipid content was observed in all the test conditions compared to control samples (highest was 16.9%). Highest lipid content of 23.3% was observed in Zn stressed conditions. However, in terms of lipid productivity, salinity stress treatment produced the highest average lipid productivity of 0.008±0.005 mgL^-1d^-1. After certain period of time (14th day), lipid content of stressed samples decreased. Oleic acid and linoleic acid were found to be abundant in all of the treatments. The study suggests that imposing stressful conditions can result in a higher amount of lipid yield from the algae biomass with a higher rate of productivity that contains important fatty acids which can be a feasible opening for biofuel production.